This invention relates to novel oligothiophenes and processes for the synthesis thereof, and more particularly, to such oligothiophenes in which the thiophene rings are cross-conjugated and annelated into a helix.
Five-membered ring unsaturated heterocycles, containing two double bonds and one heteroatom, are building blocks for conductive polymers. Polypyrrole and polythiophene are among the well-known conductive polymers with good stability and processability. These heterocycle polymers contain a pi- conjugated system (single and double bonds alternating) along a main polymer chain, linear or branched. 
Pi-conjugated compounds, particularly thiophene-containing or furan-containing compounds, are used in various industrial applications. For example, they can be used as dyes or pigments, as (semi)conductors, (electro)luminescent material or in optical and electro-optical devices such as light emitting diodes, field-effect transistors, solar cells, polarizing optical elements and rechargeable batteries, and electrolytic capacitors. General background concerning the structure, properties and uses of redox active, electroactive, conductive polymers is described in an article entitled xe2x80x9cConductive Polymersxe2x80x9d by Mercouri G. Kanatzidis published in Chemical and Engineering News, Dec. 3, 1990 and in U.S. Pat. Nos. 4,569,734; 4,640,749; 4,818,646; 4,987,042; 5,108,573; 4,758,634; 5,919,951; and 6,184,540, each of which is incorporated herein by reference.
There remains a need for improved oligothiophenes and processes for synthesizing them.
Among the several objects of the invention may be noted the provision of novel oligothiophenes and intermediates therefor; the provision of novel processes for preparing such oligothiophenes; the provision of such processes which produce oligothiophenes in the form of a helix; and the provision of such oligothiophenes which are produced by cross-conjugating and annelating thiophene rings into a helix. Other objects and features will be in part apprent and in part pointed out hereinafter.
Briefly, the present invention is directed to compounds of the formula: 
wherein X is Br or I and R1 is trialkyl with the alkyl group having from 1 to 6 carbon atoms.
The invention is also directed to intermediate compounds of the formula: 
wherein X is Br or I and Y is H or SiR1 wherein R1 is trialkyl with the alkyl group having from 1 to 6 carbon atoms.
The invention is further directed to a process for preparing compounds of the first formula above comprising the steps of
(a) converting a compound of the formula: 
wherein X is Br or I, to a compound of the formula: 
wherein X is as defined above and R1 is trialkyl with the alkyl group having from 1 to 6 carbon atoms;
(b) cross-conjugating compounds of the formula (3) above to a compound of the formula: 
wherein X and R1 are as defined above; and
(c) annelating a compound of the formula (4) above to produce an oligothiophene helix of the first formula above.